Currently various communication systems are developed and used, and a communication systems of the circular polarized wave mode is known. A circular polarized wave antenna is used for an antenna of terminal equipments in such a communication system. For example, a GPS (Global Positioning System) receiving terminal is known as the terminal equipment, and a patch antenna is used mainly for the GPS receiving antenna equipped with the GPS receiving terminal. By the way, as for the GPS receiving terminal, products of various uses are developed and used, for example, a watch having a built-in GPS receiving terminal is developed and used. But it was difficult to incorporate the patch antenna in the watch, because a clock function part is inside of the watch.
So a configuration of a conventional watch which incorporated the circular polarized wave antenna instead of the patch antenna is shown in FIG. 20 and the exploded perspective view indicating the configuration of the watch is shown in FIG. 21.
In these figures, 101 is a main body of the watch, the main body 101 consists of a main body base 111 made of metal and a band 112. The clock function part and the GPS receiving part are embedded in the main body base 111. Additionally the band 112 is intended to attach the main body 101 to an arm. In addition, on the front of the main body base 111, a display part 113, on which clock information and received information are displayed, is equipped. Furthermore, on the front of the main body base 111, a ring-like step part 111a consisting of an annular step is equipped, and a hole 114 of small diameter is formed in the ring-like step part 111a. 
An antenna part 100 formed in a ring shape is attached to the ring-like step part 111a formed around the display part 113. When the antenna part 100 is attached to the ring-like step part 111a, the level of the upper surface of the antenna part 100 is substantially corresponding to the level of the upper surface of the display part 113. The antenna part 100 consists of a dielectric substrate 121 formed in a ring shape and a C-shaped loop element 122 formed on the upper surface of the dielectric substrate. The C-shaped loop element 122 has a cut part 123, which cuts the loop in a part, to receive the circular polarized wave. Also, in the part of the C-shaped loop element 122 arranged on the dielectric substrate 121, a feed point 124a is formed at the position of a predetermined angle from the cut part 123, and a feed pin 124 is derived from a feed point 124a. 
The feed pin 124 derived from the antenna part 100 is inserted into a insertion hole 114 when the antenna part 100 is attached to the ring-like step part 111a. In this case, the feed pin 124 is coated with insulation coating, or covered with insulation tube so as to avoid directly contacting between the feed pin 124 and the main body base 111 made of metal. When the feed pin 124 is inserted into the insertion hole 114 in this way, the feed pin 124, which is a center conductor, and the main body base 111, which is a ground conductor, form equivalently the coaxial line. Also when the angle between the feed point 124a and the cut part 123 is approximately +45 degrees or −135 degrees a left-hand circular polarized wave is radiated from the antenna part 100, when the angle is approximately −45 degrees or +135 degrees a right-hand circular polarized wave is radiated from the antenna part 100.
Frequency characteristics of a voltage standing wave ratio (VSWR) in the frequency band used by the GPS is shown in FIG. 22, and radiation characteristics in a vertical plane is shown in FIG. 23, for the case of locating the conventional antenna part 100 shown in FIG. 20 and FIG. 21 on a quasi casing of the main body 101 of the watch. In this case, when the free-space wavelength at the center in the frequency band for the GPS is defined as λ, for example the circumferential length of the C-shaped loop element 122 is approximately 1.31λ, the height of the dielectric substrate 121 is approximately 0.15λ, the angle between the cut part 123 and the feed point 124a is approximately 40 degrees, the length of the cut part 123 is approximately 0.018λ.
Referring to FIG. 22, the best VSWR value of about 1.1909 is shown at 1575.4200 MHz, and the VSWR value to be less than or equal to about 1.85 is shown in the range from 1555.4200 MHz to 1595.4200 MHz.
Also FIG. 23 shows the radiation characteristics at 1575.4200 MHz of the center in the frequency band for the GPS. Referring to FIG. 23, the radiation is the strongest in the zenith direction (0 degree), the peak value is approximately −5.1 dBic. It shows that the gain decreases as an elevation angle becomes small, and in the 90 degrees direction approximately −6 dB of the gain decreases from the gain in the zenith direction, and in the −90 degrees direction approximately −7.5 dB of the gain decreases from the gain in the zenith direction.